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Groups > comp.lang.java.programmer > #33859

Re: stream filter twice

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On 2/21/2016 6:58 AM, Robert Klemme wrote:
> On 21.02.2016 04:20, Arne Vajhøj wrote:
>> If the first then I think you current code is fine.
>>
>> If the second then you will need to be creative.
>>
>> Here is my attempt to be creative:
>
> I'm a bit more old fashioned, maybe that's why I do not find the
> advantage of streams so big here.

It saves a bit of typing.

>                              I was also considering, we might not
> know how large the initial collection is.  So the cost of iterating
> twice could be significant.

Yes. That is what my alternative tried to address.

>                                                                So:
>

>          for (final myClass i : myclasscollection) {

Stream forEach really does the same as this.

>              if (i.filter())
>                  x.add(i);
>              else if (i.anotherfilter()) // "else" is optimization!
>                  y.add(i);

But if we are in micro-optimization mode, then why add to y when we
know that x is non empty?

Arne

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Thread

stream filter twice Philipp Kraus <philipp.kraus.flashpixx@gmail.com> - 2016-02-20 04:28 -0800
  Re: stream filter twice Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-02-20 08:16 -0500
  Re: stream filter twice Arne Vajhøj <arne@vajhoej.dk> - 2016-02-20 22:20 -0500
    Re: stream filter twice Robert Klemme <shortcutter@googlemail.com> - 2016-02-21 12:58 +0100
      Re: stream filter twice Arne Vajhøj <arne@vajhoej.dk> - 2016-02-21 09:52 -0500
      Re: stream filter twice Sebastian <news@seyweiler.dyndns.org> - 2016-02-22 00:13 +0100

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